Coil core of ceramic ferromagnetic material



June 15,1965 E. OLSEN COIL CORE 0F CERAMIC FERROMAGNETIG MATERIAL Filed March 1, 1963 INVENTOR EIGIL OLSEN AGENT FIG.2

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\T H u n G n n u I a F u n T H m V United States Patent 7 Claims. (Cl. 336212) The invention relates to a coil core of ceramic, ferromagnetic material. The invention has for its object to provide a core of the kind set forth, which can be manufactured in a small size in a cheap manner in large quantities and which perm-its of obtaining cheap coils or transformers of satisfactory quality (Q), suitable for many purposes.

In accordance with the invention the coil core comprises a mainly H-shaped part and a polygonal annular part disposed on the former and covering for the major part the limb portions. The coil winding can be wound without any objection on the H-shaped core portion prior to the application of the annular part and, as will be described more fully hereinafter, the two air gaps between the two core portions have a fairly large surface, so that they bring about only a small reduction of the inductance of the coil.

It should be noted that a H-shaped core of compressed powdery iron without magnetic shunt is known per se. This core is magnetically not closed and is therefore less suitable for use in a transformer and for other purposes which require a comparatively high effective permeability.

The invention will be described more fully with reference to the drawing, in which:

'(II IG. 1 shows one embodiment in a perspective view an FIGS. 2 and 3 show the same embodiment in a more complete form in a plan view and a vertical sectional view respectively.

The coil core shown in FIG. 1 of ceramic, ferromagnetic material, for example ferrite consists of a H-shaped part 1 and an annular, here rectangular part 3, said core parts being disposed one on the other so that the annular part 3 covers for the major part the yoke parts of the part 1, i.e. the limbs 2 of the H. In FIG. 1 the two core parts 1 and 3 are shown at a given distance from each other for the sake of clarity. The central connecting piece 4 of the H-shaped core part 1 is intended for the application of at least one coil winding 5 (shown in broken lines in FIGS. 2 and 3). Prior to the assembling of the two core parts 1 and 3 this winding can be directly wound on the core part 1.

The central connecting piece 4 of the H-shaped core part is preferably provided with a coil former 7 of a synthetic substance (see FIGS. 2 and 3), which former can be applied around the core part concerned in a suitable mould by compression or spra n'ng. Said coil former 7 is preferably provided with moulded flanges 9, which engage the yoke parts of the H-shaped core part 1. These flanges may be provided with thickened parts :11, which cover the yoke parts or legs of the core part 1 on the side remote from the annular core part 3. In these thickened parts there are fastened connecting members, for example, soldering pins 13, which are provided preferably at one end with a head 15, which is embedded in the insulating material .of the thickened parts 11. To the portions of the soldering pins 13 projecting beyond the material can be fastened the ends of the winding(s) 5 of the coil and the connecting Wires to be connected to said windings.

From the figures it will be apparent that the surface of the two air gaps 17 between the two core parts 1 and 3 corresponds with the surface of the yoke parts of the core part 1 and may therefore be materially larger than the surface of the section of the central part of said core part surrounded by a winding. In order to further reduce the magnetic reluctance of the two air gaps, the engaging faces of the joined core parts 1 and 3 may be ground flat. If desired an annular, in this case rectangular core part 3 may be provided, in contrast to the fig-. ures, on each side of the H-shaped core part 1. These measures can yield a comparatively high inductance and a high coil quality Q=wL/R of the windings provided on the core parts 1 and 3, even, with very small dimensions of for example 10 x 10 x 4 mms. of the core.

What is claimed is:

1. A magnetic core for an inductance coil comprising an H-shaped member of ferromagnetic material, and ferromagnetic means defining an opening and comprising at least two legs which are arranged to mate with the limbs of said H-shaped member in close contact there with over a substantial portion of said limbs.

2. A magnetic core for supporting a coil comprising an H-shaped member of ceramic ferromagnetic material, and a polygonal ring of ceramic ferromagnetic material and comprising at least two legs arranged to mate with the limbs of said H-shaped member in close contact therewith over a substantial portion of the surface of said limbs.

3. A magnetic core for an inductance coil comprising an Hshaped member of ferromagnetic material, and a hollow rectangular ring member of ferromagnetic material positioned on said H-shaped member so that a pair of opposed legs of said rectangular member are in close contact with the limbs of said H-shaped member over a major portion of the surface area of said limbs facing said rectangular member.

4. An inductance device comprising an H-shaped member of ferromagnetic material having a pair of limbs and a cross bar member, a ferromagnetic member in the form of a hollow parallelogram positioned on said I-I-shaped member so that a pair of opposed legs of said parallelogram member are in close contact with the limbs of said H-shaped member over a substantial portion of said limbs, and a winding mounted on said cross bar member.

5. A magnetic core for supporting a coil comprising an H-shaped member of ceramic ferromagnetic material, said H-shaped member comprising a pair of limbs having a flat surface, a ceramic ferromagnetic member comprising a plurality of integral legs together forming a closed ring, said ring member comprising at least two legs having a fiat surface, said H-shaped member and said ring member being positioned so that the fiat surface of said legs are in close contact with the flat surface of said limbs over a substantial portion of said limb surface.

6. An inductance device comprising an H-shaped member of ferromagnetic material, said H:shaped member comprising a pair of outer limbs having a flat surface in a common plane, a ferromagnetic member in the form of a hollow rectangle, said rectangle member having a pair of opposed legs having a fiat surface in a common plane and arranged to mate with said limbs of the H-shaped member, said H-shaped member, and said rectangle member being positioned so that the flat surface of said opposed rectangle legs closely engages the fiat surface of said outer limbs over a substantial portion of the flat surface of said limbs, and a winding mounted on one of said ferromagnetic members.

7. A magnetic core for an inductance coil comprising an I-I-shaped member of ferromagnetic material having '3) a pair of limbs and a cross bar member, a ferromagnetic member in the form of a polygonal ring having a pair of legs arranged to mate with the limbs of said H-shaped member in close contact therewith over a substantial portion of said limbs, and a coil former composed of a synthetic insulating substance girding said cross bar member, said coil former comprising a flanged portion having a widened portion on the side of said cross bar member which is remote from the contact surface of 1 References Cited by the Examiner UNITED STATES PATENTS 1,297,127 3/19 Elmer 336-233 X 2,143,298 1/39 Boucke 336-233 X 2,599,068 6/52 Potter 336-233 X 2,692,978 10/54 Galt 336-233 LARAMIE E. ASKIN, Primary Examiner.

said limbs, and a conductive element mounted in said 10 JOHN F. BURNS, Examiner.

widened portion. 

1. A MAGNETIC CORE FOR AN INDUCTANCE COIL COMPRISING AN H-SHAPED MEMBER OF FERROMAGNETIC MATERIAL, AND FERROMAGNETIC MEANS DEFINING AN OPEINING AN COMPRISING AT LEAST TWO LEGS WHICH ARE ARRANGED TO MATE WITH THE LIMBS OF SAID H-SHAPED MEMBER IN CLOSE CONTACT THEREWITH OVER A SUBSTANTIAL PORTION OF SAID LIMBS. 